Adjustable collar



FIG. 1 is a perspective view of an adjustable collar, showing my new design;

FIG. 2 is a perspective view thereof;

FIG. 3 is an enlarged front elevational view of FIG. 2;

FIG. 4 is an enlarged rear elevational view of FIG. 2;

FIG. 5 is a left-side elevational view of FIG. 2, the right-side elevational view being a mirror image thereof;

FIG. 6 is a top plan view of FIG. 2; and,

FIG. 7 is a bottom plan view of FIG. 2.

The broken lines in FIG. 1 showing a dog depict environmental matter and form no part of the claimed design. The remaining broken lines represent stitching, and are part of the claimed design. 

CLAIM I claim the ornamental design for an adjustable collar, as shown and described. 